But in a new twist, at least two of the individuals that tested positive for brodifacoum denied using spice, and both tested negative for synthetic forms of marijuana.

They did admit to marijuana use and one tested positive for marijuana metabolites.

A third individual also tested positive for marijuana metabolites but the screen for brodifacoum was not performed.

In the most recent case, one week ago, the individual admitted synthetic marijuana use.

Alfred Aleguas, PharmD, D.ABAT, director of the Poison Information Center says they don't yet know if a test for brodifacoum was done.

Aleguas believes even without confirmation, it's unlikely any of these patients' signs and symptoms would have been caused by anything else but rat poison. What they haven't been able to do is link three of the cases back to synthetic marijuana.

"We're not really sure where it's coming from. It's such an effect that it couldn't be from the commercially-available anticoagulants that you can go to any of the box stores and buy. Those are very low concentrations and really not much of a problem at all. These are at concentrations enough to produce that prolonged inability to clot," Aleguas said.

Symptoms of rat poison exposure include unusual bleeding, including blood in the urine, nose or gums, vomiting or coughing blood, wounds that keep oozing, and heavy menstrual bleeding.

Bleeding can also occur in the head, causing stroke like symptoms. Internal bleeding, especially after trauma, can cause bruising and pain in the side or abdomen.

The risk of profound bleeding is also putting blood banks on alert.

In June 2018, the FDA issued a statement saying they had received several reports of plasma donors who used synthetic cannabinoids contaminated with brodifacoum. There was no risk to patients however, since the source plasma is used for further manufacturing and is not directly transfused into individuals.